Firearm



July 3, 1945. c. E. SIMPSON FIREARM s Sheets-Sheet 1' Filed Aug. 21, 1941 Clarence E E 1im :aun

C. E. SIMPSON July 3, 1945.

FIREARM Filed Aug. 21, 1941 3 Sheets-Sheet 2 July 3, 1945. c. E. s|Ml =s0N FIREARM Filed Aug. 21, 1941 1 3 Sheets-Sheet 3 Elurence E- Simpson chine rifle which is similar to the one Patented July 3, 1945 UNITED STATES PATENT OFFICE FIREARM v Clarence 15]. Simpson, Springfield, Mass. Application August 21, 1941, Serial No. 407,715

(Granted under the act of March 3, 1883, as v amended April 30, 1928; 370 0. G. 757

22 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon. I

This invention relates to an automatic firearm.

An object of this invention is to provide a firearm which might be fired at two diiIerent rates.

Another object of this invention is to provide a firearm which may be set in three positions, namely: (1) rapid rate automatic fire, (2) medium rate automatic fire, and (3) safety.

Another object of this invention is to provide a rate reducing mechanism in the Browning madescribed in the Browning Patent 1,393,022.

Another object of this invention is to provide a rate reducing mechanism in a'firearm so as to decrease the normal rate of fire. from a value approximately 600 shots perminute to a value approximately 350 shots per minute.

The specific nature of the invention as well as other objects and advantages thereof willclearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Figs. 1 to 5 are fragmentary elevational views of the operating section of a gun in partial longitudinal section. v

Fig. 6 is a plan view of the sear I l.

Fig. 7 is a section through the center of the sear H.

Fig. 8 is a side View of the sear release stop lever [4.

Fig. 9 is a plan view of the sear release stop lever l4.

Fig. 10 is a plan view of the change lever Ill with the portion adapted to ,be manipulated by hand extending perpendicular to the plane of the paper.

Fig. 11 is a side view of the change lever l0 shown in Fig. 10.

Fig. 12 is an end view of the change lever shown in Fig. 10.

Fig. 13 is a View taken along line I3| 3 in Fig. 12.

Fig. 14 is a view taken along line i l-14 in Fig.511.

Fig. 15 is a view taken along Fig. 11.

Fig. 16 is a fragmentary elevational View of a portion of the gun in the region of the trigger guard.

Fig. 17 is an end view of Fig. 18, and I Fig. 18 is a sectional view taken along line 18-|8 in Fi 17.

line |s--| s in In Fig. 1, the firearm mechanism is illustrated in condition for firing fully automatic at the medium rate, with the bolt cooked and the trigger not pulled. Fig. 2 shows the firearm mechanism of Fig. 1 just after the trigger has been pulled While Fig. 3 shows the condition of the mechanism of Fig. 1 when the bolthas returned to counterbattery position after firing of a cartridge and the actuator of the delay mechanism is in its rearward position. g V

In Fig. 4, the firearm mechanism is illustrated in condition for firing fully automatic'at the high rate, at a point after the'trigger has been pulled and the bolt is returning to its counterbattery position.

In Fig. 5, the firearm mechanism is illustrated in the Safe condition. I

Reference will be had to the accompanying drawings wherein like numerals designate like parts and the operation and description of the parts of the rifle will be described under the following headings:

1. Description of parts in the rifle stock.

2. Description of scar and trigger mechanism.

3. Operation of rifle when fired at medium rate (Figs. 1-3).

4. Operation of Description of pwr'ts in the rifle stock The main operative parts in the stock for producing a delayed action so that the rifle may be fired at a medium rate are: the sear release 2|, stop 24, and the spring biased actuator 23. These parts are operated only when the rifle is fired at the medium-rate. The bufier cups 21, cones 28 and spring 29 are well known components in the Browning rifle; their only function is to serve as a bufier for checking the rearward movement of theslide and these components have no bearing on the mechanical functioning of the rate reducing mechanism but are operativein absorbing at least some of the slide recoil energy when the rifle is fired at all settings.

The buffer tube 38 is held on the rifle receiver 36 by cooperating screw threads in those elements at one end of the tube 38 and. the other end of the tube is partially closedby the bufler nut 30 which is screwed on the last mentioned end. The buffer nut 30 is rigidly fastened to the inner actuator guide tube 26 by means of a brazed connection or by mechanical ineans with an end of tube 26 extending within'and concentric to the bufier tube 38; the other end of tube 26 is screw threaded.

rifle when fired at high rate The buffer spring 29 which is disposed in buffer gral with the bufier tube and serves to confine the buffer l8 within the buffer tube.

The sear release 2| has a longitudinal portion 2 la and a portion 2 lb perpendicular thereto. The longitudinal portion has a groove 2|c formed therein within which the key l9 extends. cylindrical shaped buffer |8 has a square shaped axially extending hole |8a and a longitudinally extending square shaped groove |8b Within which the key I9 is disposed. Four slots 381) are provided in the circular shoulder, 38a as a matter of convenience in aligning. the parts but only one of those slots is used for the passage of the key IS; the particular aperture chosen being that one which allows portion 2|b of the sear release 2| to abut the rifle sear II in the final assembly. Shims 35 of various thicknesses are provided and are to be disposed between the shoulder 380 on the buffer tube 33 and the receiver 36 so that the portion 2|b of the sear release 2| might be more accurately positioned with respect to the rifle sear ll.

The stock is held on the receiver by the sleeve assembly composed of sleeve 33, collar 32 and stop 24. The only component in this assembly essential to the function of the rate reducing mechanism is the stop 24. The washer 3| prevents the stock retaining sleeve assembly from unscrewing. The collar 32 may be fastened to the sleeve 33 by brazing or by mechanical means. The step has a screw threaded, portion which is adapted to engage the screw threaded portion on the actuator guide-tube 26. The stop 24 is fastened to the sleeve 33. bya pin 50'passing through holes in those two elements but it is understood that other fastening meansmay be used. The stop 24 has a slot 2411 within whicha mechanical tightening tool may be inserted and a hollow portion 24b-which vents the interior of tube, 26 and lightens the stop 24.

Acircular shoulder 240 is provided on stop 24 for one end of coil spring'25; the other end of spring 25 abuts the circular shoulder 23a of actuator 23 with the result that the actuator 23 is biased in engagement with the sear release 2|. In the medium firing rate. position and when the trigger i depressed (Fig. 2) the sear release 2| projects a small amount beyond the buffer l8 and is adapted to be struck by the rifle slide near the end of itsrecoil stroke; the impact is transmitted to the actuator 23 which is thus caused to move against the stop 24 (Fig. 3) and then the spring 25 returns the actuator 23 to abutting position with the sear release 2 l. The time of flight of the actuator 23 determines to a large extent the rate at whichtherifle is fired in-the-medium rate arrangement.

It is noted that theshape of groove 2|c (Fig. 18) .in the sear release 2| is such that there is practically no frictional engagementbetween the sear release 2| and key .lawhen the sear release is in its rearmost position. The shape of groove 2|c was chosen to afiord proper form for heat treatmentofthe component.2|;, U I i The Description of sear and trigger mechanism The trigger i3 is pivoted to the trigger guard by trigger pin |3c. The connector 15 fits loosely in the trigger, the'lower notch |5a riding on the connector pin |5b which is held in the two parallel oppositely disposed walls |3a of trigger 3. The upper edge |'5c of the connector comes in contact with the surface I la (Fig. '7) on the front end of the sear II when the trigger is raised by pulling it. The sear H is pivoted near the rear end of the trigger guard 5| by the sear pin ||b which passes through holes (not shown) in the trigger guard. The rear end of the sear is provided with a nose ||c which engages the sear notch |2.in the side 34. The under surface ||a of the front end of the sear engages the connector edge |5c when it is raised by the action of the trigger by pulling it. The sear spring 52 is held in grooves 5|c in the trigger guard. This spring is of the leaf type, the middle tongue 52a bearing against the connector |5- holding this latter part in position. To outside tongues. 52b of the sear spring bear downward against the. forward ends lld of the sear.

The change lever ID extends. laterally. through the trigger guard, being held in place by the front tongue Ila. of the change lever spring |1. This. tongue also engages. in notches Illav around the shaft of the change lever, thus holding the change lever in the various positions. The handle of the change lever extends upward along the left side of the. receiver on which. is marked the positions: F for medium rate of fire, A for rapid rate of fire, and S for safety (Fig. 16.).

The cuts and lugs on the underside of the change. lever shaft control the action of. the. trigger and.

connector, thus giving the classes of fire mentioned. The'change lever spring isheld inthe,

trigger. guard by means of grooves 5|d. The scar release stop lever l4 which is assembledon the sear abuts the rear tongue I'Ib of this spring.

The change lever I0 is a cylindrical bar which has three shallow longitudinal slots Illa cut onv top of the bar, as the handle is held vertically; the side of the bar is slotted in such. a way: as. to leave a little tongue of metal |0b in the center. and at the lower edge of the slot. The trigger |3 has two spacedwalls |3a through: which the connector pin |5b passes and which are adapted to straddle the tongue lllb'andmove with respect thereto when the lever is set on F" or A; when the lever is set on the S position the upper edges |3b of the walls |3a abut against the solid of the tri ger.

When the lever I0 is set in the A position (rapid rate of fire) and the trigger is pulled the head |5c of the connector. is-raised and: cannot be tipped forward; the tongue |0b on the change lever engages the toe |5d of the connector as the trigger is pulled and prevents the connector from rotating.

When the change lever I0 is in the F position (medium rate. of fire) the tongue. IDb on the change lever does not engage the toe |5d of the connector, and the head |5c of the connector can be tipped forward. When the trigger is squeezed, at first the head of the connector rises and thereby depresses the sear nose ||c so that the slide is allowed to go. forward. If the squeeze of the trigger is continued. the cam surface |5e on the connector rides on thefree end of arm 55, and the head |5c of the connector is'cammed forward against the. pressure of'the center leaf 52a of the sear spring;52. Thea-other end of the arm 55 is fastened at 55a;

In the Browning automatic rifle the cam surface |5e on the connector is commonly referred to as the sear carrier ramp and a cam projection on the sear carrier (not shown) engages the surface lfie to produce the functions ascribed to the arm 55.

The upper edge I50 of the connector disengages the surface Ha of the sear and the two outside leaves 52b of the sear spring depress it, ,and the sear nose c is thereby raised up in the path of the slide and engages the slide notch l2 when the slide moves back; thus if there were no other means in the rifle only one shot could be fired. The only function of the change lever ID in the F position is the limiting of the upward travel of the trigger when its upper rear surfaces of spaced walls |3a strike the top of the slot in the change lever, which in this position is turned down. The forward end I6 of the sear release stop lever projects beyond and lays on the front end of the sear so that when the connector I5 slips 01f the surface ||a of the sear, the sear release stop lever M will be engaged at l6 by the connector and rotated whereby the sear release 2| will be released; the sear release 2| would then be free to move as long as the trigger is depressed. The sear release stop lever I4 is centrally mounted within the sear II with the forward end of the stop lever projecting beyond and lying on the upper surface of the sear and with the rearward end of the stop lever biased against the underside of scar II by the to the trigger guard spring llb; the rearmost end of the stop lever is adapted to abut the release 2| so as to prevent axial movement thereof.

In the A position the end of connector I5 is prevented from rotating by cooperation of tongue Illb on the change lever I with toe |d on the connector l5 so that in that position the connector I 5 is prevented from coaoting with the stop lever with the result that the sear release 2| is prevented from operating; the sear H which carries the stop lever 4 is moved somewhat as the trigger is pulled in'the A position but that movement is not sufficient to cause disengagement of the stop lever M with sear release 2|.

Operation of rifle when fired at medium rate With the lever l0 set at the F position-the rifle is placed in the ready to fire position by retracting slide 34 by hand until the sear engages the notch I 2 in slide 34.

Upon pressing the trigger l3 the spaced walls |3a on the trigger pass up in the slot of the change lever l0, straddling its tongue I012, and carries the pivoted connector l5 upwards into engagement with the surface I la on the sear so that the sear H is pivoted about the sear .pin ||b out of engagement with the notch l2 in slide 34; slide 34 then moves forward. Further movement of the trigger will causethe upper edge |5c of the connector I 5 to slide off the sear surface ||a against the action of the connector spring 52a' and engage the outer end i6 of the sear release stop lever |4 whereby disengagement of the stop lever. from the sear release 2| is produced and the sear H is allowed to engage the. notch l2 in slide 34 when it returns in recoil. At the end of the recoil stroke initially the slide 34 strikes the sear release 2| causing it to impart an impact to the, actuator 23 and finally the slide 34 strikes .the buifer 8 which imparts the re-' mainder of the kinetic energy of the slide to the cups and cones21, 28 in a .manner well-understood in the art; then, as theslide :moves forward the sear nose ||c engages the notch 2 .in the slide and arrests further motion of the slide but in the meantime the actuator 23. moves down the tube 26 against the action of sprin 25, hits the stop 24 and is moved forward by the compressed spring 25 which causes the actuator to strike sear release 2| and causes it to-ride up on the cam face Hf of the sear, depressing it and thus causing the sear nose No to be. disengaged from the notch l2. The slideis then free to move forward but only after its motion had been delayed a time interval represented by the time of travel of the actuator 23 from its for.- ward position to its rearmost position and back to its forward position. As long as the trigger is depressed the searrelease stop lever I4 will be disengaged from the sear "release 2| and it will cause the slide to be releasedafter each rearward movement of the slide. When the trigger is released the sear release 2| is prevented from moving by the sear release stop lever M which is biased into position by means of spring 12).

Operation of rifle when fired at high rate When full automatic fire is desired, it may be obtained by setting the lever 0 corresponding to the A position on the receiver and pulling the pressing the trigger the connector |5 moves upward and is prevented from pivoting by the change lever bar tongue lflb which engages the toe |5d of the connector. As long as the trigger is depressed sear nose He will be held out of engagement with the slide notch I2 and since the operation of scar release 2| is not. necessary to the functioning of the.,rifie in this arrangement sear release 2| is held against movement by the sear release stop lever M. The slide having no obstructions in its path will then be capable of moving as long as the trigger is de- I pressed; when the trigger is released sear nose Ho will engage the slide notch l2 and arrest the motion of the slide.-

It will be noted that when the gun is set in the slow firing position it mayat any time be immediately converted to rapid fire by relaxation of the trigger and back to slow fire by increased pressure on the trigger.

I claim:

1. In a firearm, a, buifer enclosing member, a sear release having a body portion with a groove therein and a projection, a, spring pressed buifer projecting out of one end of the member and having a hollow portion adapted to hold said body portion which extends substantially parallel to the direction in which the buffer is adapted to move, and a key passing through the member and buffer and adapted to have one of its ends in the sear release groove.

2. The same as in claim 1, and the enclosing member has a plurality of holes through which the key may be inserted.

3. The same as in claim 1 and the end of the key and sear release groove are adapted to form a guide.

4. In a firearm, a buffer tube, a sear release, a spring pressed buifer having a hollow portion adapted to partially confine the sear release and projecting out of an end of the tube, a second smaller tube projecting into the other end vofthe bufieri'tube, means for joining the twotubes, a seat release actuator in and'adapted to move'in the smaller tube, a stop in the second tube, and resilient means disposed between the: actuator and the stop.

5. In a firearm, a buffer tube, a sear release having a groove, a spring pressed buffer extending beyond the end of the tube and having a hollow portion which is adapted to partially confine the sear release, and a fastener passing through the tube and buffer and into the scarrelease groove.

6; In a firearm, a buffer enclosing member, a sear rel'ease, a spring pressedbuffer extending beyond the end of the buffer enclosing member andhaving a hollow portion whichis adapted to partially confine the sear release, means for confining the buffer in the member, and means for allowing. a limited movement betweenthe buffer andthe sear release.

7. In a firearm, a buffer enclosing member, a sear release, a spring pressed buffer extending beyond the end of the bufier enclosing member, a spring pressed sear release in the enclosing member and extending beyond the bufier, means for confining the buffer in the enclosing member, means for confining the sear release in the enclosing member, and means for allowing a limited movement between the sear release and the buffer.

8. In a firearm, a receiver, a stock having two large-hollow portions separated by a smaller connecting hollow portion, a buffer tube disposed in one of the large hollow portions, a sear release, a spring pressed buffer having a hollow portion adapted to partially confine the sear. release and projecting beyond one end of the tube, means for fastening the last mentioned end to the receiver, means for holding the buffer and sear release in the tube, a second smaller tube passing through the smaller connecting hollow portion and having one of its ends projecting into the buffer tube at itsother end, means for fastening the last two mentioned tube ends, an actuator disposed in the second tube and adapted to abut the sear release a plug in the other end of the second tube, resilient means disposed between the actuator and the plug, a sleeve surrounding the last mentioned end of the second tube and extending into abutting relation with the stock portion which defines the smaller hollow portion, means for fastening the sleeve to the plug, and means for fastening the plug to the second tube.

9. In a firearm, a slide, a, sear cooperating therewith, a trigger for disengaging said sear from said slide, auxiliary means for disengaging said sear from saidslide, said auxiliary means arranged to receive an actuating force from said slide, and a stop cooperating with said auxiliary means normally rendering said auxiliary means inoperative, said stop arranged to be positioned by the firing motion of said trigger to render said auxiliary means operative.

10. In a firearm, a slide, a scar cooperating therewith, a trigger for disengaging said sear from saidslide, auxiliary means for disengaging said sear from said slide, said auxiliarymea ns comprising a member mounted for reciprocating movement, said member arranged'tobe forced in one direction by said slide and to disengage said sear from said slide during itsreturn movement, and a stop cooperating with said auxiliary means, said stop being positionable to prevent disengagement of the sear b said auxiliary means,

' '11. In av firearm, a slide, a sear cooperating, therewith, a trigger unit for disengaging said sear from said slide, auxiliary means for disengaging said sear from said slide, said auxiliary means arranged to receive an actuating force from said slide, and a stop cooperating withsaid auxiliary means, said stop being positionable to prevent the disengagement of said sear by said auxiliary means, and adjustable meansto control the firing position of said trigger unit, said sear and stop being so constructed and arranged that the trigger unit in one position disengages the sear and maintains said stop operative and in another position is free of the sear and renders said stop inoperative without influencing coaction betweenthe slide and sear.

12., In a firearm, ,a slide, a scar cooperating therewith, a trigger'unit for disengaging said sear from said slide, auxiliary means for disengaging said sear from said slide, auxiliary means comprising a member mounted for reciprocating movement, said member arranged to be forced in one direction by said slide and to disengage said sear during its return movement, a stop cooperating with said auxiliary means, saidstop being positionablerto prevent the disengagement of said sear by said auxiliar means, and adjustable means to control the firing position of the said trigger unit, said scar and stop means being, so constructed and arranged that the trigger unit in one positiondisengages the scar and maintains the stop operative and in another position is free of the sear and renders the stop inoperative'without influencing coaction between the sear,

13. In a firearm, a slide, a sear cooperating therewith, a trigger unitfor disengaging said sear from said slide, auxiliary means for disengaging said sear from said slide, said auxiliary means comprising amember mounted for reciprocating movement, said member arranged to' be forced in one direction bysaid slide and to disengage said sear during its return movement, and a stop cooperating with said auxiliary means, said stop being positionable toprevent disengagement of the sear by said auxiliary means, said trigger unit being arranged to successively engage the-sear and to engage and render the stop inoperative, being free of the sear when the stop is engaged, and means to limit the trigger motion to positions corresponding to said engagements.

1-4. In a firearm, a slide havinga recess, a sear cooperating therewith, spring means biasing said sear into engagement in said recess, atrigger unit for disengaging said sear from said slide;- auxiliary means for disengaging said sear from said slide, said auxiliary means comprising a member mounted for reciprocating movement, said member arranged tobe forced inone direction. by said slide and to disengage said sear during its return movement, a stop cooperating with said auxiliary means, said stop being positionable to prevent disengagement of the sear by said auxiliary means, spring means biasing said stop into blocking engagement with said auxiliary means, said trigger unit being engageable with said sear in one-firing position of thetrigg'er unit to disengage said sear from said recess and maintain said stop in blocking engagement with said auxiliary means, said trigger unit-being free of said sear in an advanced firing position and engageable with said stopto remove said stopfrom blocking engagement with said auxiliarymeans and means to selectively limit the motion of the trigger unit toei ther of said positions;

slide and 15. In a firearm, a slide having a recess, a sear cooperating therewith, spring means biasing said seal into engagement in said recess, a trigger unit elfective in one firing position to disengage said sear from said slide, auxiliary means for disengaging said sear from said slide, said auxiliary means comprising a sear disengaging member mounted for reciprocating movement, said member arranged to be forced in one direction by said slide and to disengage said sear during its return movement, a stop cooperating with said auxiliary means, said stop being positionable to prevent disengagement of the sear by said auxiliary means, spring means biasing said stop into blocking engagement with said auxiliary means, said sear and stop each comprising centrally pivoted arms, one arm each of said stop and said scar arranged to be engaged by the trigger unit, said trigger engaging arm of said stop extending beyond said trigger engaging arm of said scar and 'angularly spaced therefrom so as to be actuable by the trigger unit in a more advanced firing position than that required to disengage thesear, a pivoted member in said trigger unit adapted normally to engage said sear arm, cam means for removing said pivoted member from contact with said sear arm by movement of the trigger unit to said more advanced firing position where the said arm of the stop is contacted by said pivoted member, and means to selectively limit the trigger unit motion to either of said positions.

16. The combination set forth in claim 15 wherein said sear and stop means have their pivotal mounting on a single shaft.

1'7. In a firearm, a slide, a sear cooperating therewith, a trigger for disengaging .said sear from said slide, auxiliary means for disengaging said sear from said slide, said auxiliary means comprising a member arranged for reciprocating longitudinal motion in the general path of said slide, said member arranged to be forced in one direction by said slide, resilient means opposing the motion of said member, said auxiliary means arranged to disengage said sear upon the return of said member under the bias of said resilient means, and a stop cooperating with said auxiliary means normally rendering said auxiliary means inoperative, said stop arranged to be positioned by the firing motion of said trigger to render said auxiliary means operative.

18. In a firearm as in claim 15, buffer means for said slide, said sear disengaging member being mounted in said buffer for longitudinal motion in the general path of said slide, an inertia member mounted for reciprocating movement in said bufier and arranged to be actuated by said sear disengaging member, and spring means biasing' said inertia member into contact with said prises a bolt selectively rotatable into a plurality of positions and having an arcuate slot and a central boss in said slot arranged to engage said toe in one rotatable position of said bolt.

20. In a firearm, a slide, a sear cooperating therewith, trigger means having two firing positions, said trigger means operating to disengage said sear from said slide in'one of said firing positions, auxiliary means for disengaging said sear from said slide, said auxiliary means being inoperative in said first trigger firing position, said auxiliary means arranged to be rendered operative by said trigger means in said second firing position and comprising a member mounted for reciprocating movement, said member arranged to be forced in one direction by said slide and to disengage said sear from said slide during its return movement.

21. In a firearm as in claim 10, bufier. means for said slide, said sear disengaging member being mounted in said buffer'for longitudinal motion in the general path of said slide, an inertia member mounted for reciprocating movement in said buffer and arranged to be actuated by said sear disengaging member and spring means biasing said inertia member into contact with said sear disengaging member.

22. In a firearm, a slide, a sear cooperating therewith, trigger means having two firing positions, said trigger means operating to disengage said sear from said slide in one of said firing positions, auxiliary means for disengaging said sear from said slide, said auxiliary means being inoperative in said first trigger firing position,

' said auxiliary means arranged to be rendered operative by said trigger means in said second firing position, said auxiliary means comprising a sear disengaging member mounted for reciprocating movement, said member arranged to be forced in one direction by said slide and to disengage said sear from said slide during its return movement, buffer means for said slide, said seardisengaging member being mounted in said buifer, an inertia member mounted for reciprocating movement in said bufier and arranged to be actuated by said sear disengaging member, and spring means biasing said inertia member into contact with said sear disengaging member.

CLARENCE E. SIMPSON. 

